Ferrite Rods and Litz wire for a DIY Pinpointer?

[Brian Donaldson]

Hi all I am a newbie so please forgive me I am just wondering if a Guru can help my understanding and put an end to my confusion. My issue is because Pinpointers are really expensive for the ones that work really well I thought I would make one. (Is this a foolish thing to do???)

Anyway just watching other peoples efforts with DIY Pinpointers on Utube and here I am just wondering if a DIY Pinpointer can detect at say 5 centimeters if you were to wind Lintz wire around a Ferrite rod ( apparently these are used a lot in Radio reception ) for a coil would you then expect to increase your detection measurement? And if so to what amount? In addition why is this so?

Thanking you all in advance.

Brian.

[waltr]

Yes, making a pinpointer with a ferrite rod does work.
Distance is dependent on size of target. It will detect a larger coin at 5cm and a coke can at >10cm.

Here is the pin pointer I built from Teemos' design.
https://www.geotech1.com/forums/show...483#post241483

[Skippy]

"Is this a foolish thing to do?"
These days, commercial pinpointers are readily available at sensible prices, so yes, it's foolish. Only make your own one for the technical challenge/fun/satisfaction , or because you're wanting something niche and not commercially available ( discrimination? sensitivity to really tiny targets? unusually large range? ). [One of the Minelab ProFinds has discrimination, just for info]
Many people have found the cheap Chinese "copy" pointers work OK, look on detecting forums to see what foks have tried ... one brand name I see mentioned is GP. But I would recommend saving up and buying a decent one, not all are expensive, think of it as an investment, that will last many years.

You didn't say whether you wanted PI or VLF type. PI are better for the beach, as the wet sand doesn't cause falsing , but they aren't so sensitive to tiny items, and are more likely to interfere with your detector. There's plenty of choice in VLF's, which are the most popular type for general hunting.

This '50mm' range figure: what exactly are you wanting to find at 50mm ? Medium-sized coins ( US 5 cent , UK 20p ? ) Or Grain-weight gold nuggets?
Commercial machines will find coins at 50mm.

With ferrite rods, the key to getting greater range is to use a larger diameter rod. The very common 9mm-ish 'radio' rod limits you, if you can get 1/2" ( 12.5mm) rod, you will do better. Multiple rods in a bundle is an experiment I've yet to try. 3 rods should bundle OK ( they are never straight, though) , or 5/6/7 around a non-metal core would be an interesting experiment.
Litz wire is really only relevant to PI pointers, and I don't think it's worth it, though if you have some, do try it. It's possibly worth trying a 'halfway' solution, winding with multiple strands of thinner ECW, rather than one solid wire.
If you're making a VLF, the way you wind the coil is relevant - scramble-wound can give different results to perfectly wound.

[ionut_mtb]

I’m using gp pinpointer from aliexpress, cheap, no false signals, auto tune every time you start, detection depth is not so good but you can do the job with it.

[Carl-NC]

As Skippy said, build a pinpointer for the fun of it, not for performance or economy. There are 3 predominant approaches:

• Proximity: Garrett Propointer, old White's Bullseye, old Minelab ProFind.
• VLF: White's TRX, new Minelab ProFind, XP MI4/6.
• PI: DetectorPro PistolProbe, Fisher F-Pulse.

Proximity (energy-theft) is the easiest but least performance. It tends to brick-wall at about 5cm on typical coins.
VLF can go much deeper and can discriminate, but is a very difficult design (I did the coil & analog circuitry for the TRX, coins to ~10cm).
PI is fairly simple and still can get the depth (I designed the Fisher F-Pulse, coins to ~8cm).

If you want raw depth on coins and best salt-water performance, then PI is the easy choice. If you want good response to subgrain nuggets then VLF might be the choice, though I'm pretty sure a well-designed PI could also do it.

[timekiller]

Hello everyone . My pinpoint is according to the scheme of eddy71 malish V2. The search coil is on a ferrite from a cable filter. Acept 5cm range 1 euro coin, discrimination. An excellent device for no money . No litcendrat wires .

[Brian Donaldson]

Thanks Skippy for your input I am however just wondering why do you get different results for scramble wound as opposed to perfectly wound?
Another thought I have is using two 9mm Ferrite rods bundelled together with the coil being wound around them which as a consequence would create an 'Oval' shape rather than circular which may make the coil more sensitive to targets ... what are your thoughts??
On another note I am looking to make a DIY Pin pointer for the reasons you have already indicated but also from an education point of view whereas I could learn some things I had not learnt before and therefore improve myself.

Thanking you in advance for your reply.
Brian.

[Skippy]

Two rods ? Sounds odd. It won't be symmetrical, and you'll still need a large tube to house it in.
I don't know why scramble vs neat was different. It was a practical observation whilst hacking a CS209 based pinpointer, so perhaps the peculiarities of how that IC functioned were relevant.

[Carl-NC]

Oval won't help, but any increase to cross-sectional area will. Including oval.